<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=375">
  <title>Title</title>
  <style>
    *{
      padding:0;
      margin:0;
    }
    #root{
      width: 345px;
      height: 150px;
      background: skyblue;
      margin:15px auto;
      border:1px solid red;
    }
  </style>
</head>
<body>
<div id="root"></div>
</body>
</html>